include new features in publication plot exports to CSV, Grace, Origin & Igor plots

[briantoby]

As per #72, #82 and #81, there are a number of new powder diffraction plot features now in the on-screen publication plots:

• full-length tick marks
• HKL labels
• phase partials
• specify x & y plot limits

The GSASIIpwdplot.py routines CopyRietveld2* routines (...2Grace, ...2Origin, ...2Igor & ...2csv) need a review to see if all these new features can be transferred to these exported plots.

[briantoby]

@ConradSciResa This will need your attention if you want to update the Origin publication plots to use the new features. The changes to the CopyRietveldPlot routine allow the above to be used, but not yet any of the CopyRietveld2... routines. Let me know if you have any questions.